Electron tube oscillator circuit



J y 1944. w, D. HERSHBERGER 2,354,262 1 ELECTRON TUBE OSCILLATOR CIRCUIT Filed Feb. 27, 1.942

Patented July 25, 1944 Y assazsa I it Q v I h William D. Hershbe'rger, Haddonfield, N. J., as- 1 signor to Radio Corporation of America, a. corporation of Delaware 1 This invention relates generanyte electron discharge tube oscillation circuits and particularly to oscillator circuitsin which a plurality of fre,. quencies can be produced simultaneously or selected harmonics of ;a fundamental frequency can be accentuated or suppressed.

- Previous circuits have been devised which pro vided for simultaneous generation of a plurality offrequencies in an oscillator circuit. However, this invention utilizes new and improved methods of generating and, control-lingsuch' oscillations in an extremely simple electrical circuit. The invention also provides means for accentuating or suppressing any selected harmonic ofthe fundamental oscillator frequency, by utilizing a multiresonant oscillationcircuittuned to the fundamental and selected harmonic frequencies.

An object of the invention is to provide a new and simple method and circuit for simultaneously producing a plurality of frequencies ina single oscillation circuit. .Another objectisto'provide pressing selected harmonics of: the fundamental frequency in an oscillation circuit. I

The invention will best be understood by reference to the drawing, of which Fig. 1,is a sche-' matic'diagram of a typical bi resonant circuit, Fig. 2 isa schematicdiagram of the same circuit showing equivalent reactance values for-one selected frequency, Fig. 3 is aschematic diagram of the same circuitshowing equivalent reactance values for another. selected frequency, Fig. 4 is'a" schematic diagram of an oscillator circuit, and

Figs. 5 and 6 are schematic circuit diagrams of modifications of the circuit of Fig; 4. Similar reference characters are applied to similar circuit elements in Figs. 4,- 5 and 6.

Referring to Fig. 1 of the drawing, a typical bi-resonant-or multieresonantcircuit, of the type usefulfor the'invention, is provided. A first inductance L is "connected in parallelrelation with a first capacity C. A second inductancePL is connected in series relation with a second capacity QC. 'Ihe'parallel-resonant circuit L; C is corinected in'parallel relationwith the series-resonant circuit PL, QC. Arbitrary values of inducnot necessarily be of harmonic relation.

The connections of the left hand portion of I Figure 2 correspond to the circuit of"Fig.-1 and the membersindic'ate thel'r'eactance's in the various branches of the circuit of Fig. 1 at 49.2 kc. Inductive reactance is shown as positiv quantities and capacitive reactance as negative tion of Fig. 3 is the equivalent circuit at 246 kc. wherein the parallel circuit L, C becomes an invide. a resultantparallelcircuit which re n es a grid bias is obtained by a; conventiona cath de rents at the two resonant frequenciesiare oppos;

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quantities. The centerfportio' fFig. 2 the equivalent circuit at 49.2k'c. where'ir jfth series circuit PL, QC becomes a capacitive rea 8 770 ohms. The right handpo'rtion o f.,F1g. I a"further, equivalent circuit' wherein the capac tances combine to provide a resultant par circuit which resonates at 49.2 kc.

"The connections of the left handflp'orti ot Fig. 3 also correspond to the circuit of'Fig'."'1 and r the numbers indicate the reactance relations in the same circuit at 246 kc; Inductive reactance is shown as positive quantities and capacitive reactance as negative quantities. The center porductive reactanceof 21,000 ohms. The right hand portion of Fig; 3 is a'further equivalent circuit wherein the inductances combine, .t o proa t.246 kc. .Fig. .4- is a diagram. of an electron tube oscillation circuit utilizing .thelbfcircuit of Fig 1 as a.part,of the rlod e. V The anode of tubeHI -is connected. to one nd ofnthe parallel-resonantcircuit consisting. ;of a, first inductor 3 and a first capacitor 4,, and to one; end;. of the series-resonant.circuitcomprised of, 0nd inductor 5 and a second capacitor}:-

I other terminal of .the bi-resonant circuit s cone nected to the anodevoltage-soure 'I he,.ccn-. trol electrode of tubeI- isconnected=.;to; a=third inductor 2 which is coupledto, thefirst nductor;

3. The coupling coil 2 isagrounded. table resistor '7, and bypass, condenser f 8. 1 '.,'Ihi s circuit W111 oscillate at 49.2 kc. and: provide; -a.-; l .'0ng fifth harmonic at 246 kc. It will be' seenzthfietfl the currents at both frequencies in -the :firstycg il 3 are in phase, and the amplitude*ofoscillations at the two frequencies depends'on the values of P and Q as hereinafter explained. Fig. 5 is a modificationoft-theciro in which the control electrode 'isconnected to 1' th third inductor i! which-is-coupleditfi; the

second inductor 5 of the series-resonantcircuit; I The coupling coil 2, is groundedw. Thiscircuitwill. provide oscillations at the high frequency resonant point only, in this {case 2'46 kc.j;i'-Ihe-.cur.-

ing in the second coil. 5 and regeneration":occ'urs only' at the higher frequency with thesconnec'tion j I shown to the third coil 2. i aw"? Fig. dis a modificationiof the-circuitof'Fi g in which the direction of the winding of the-:cou--'- pling coil 2 is reversed with'respect to=the'win-d-' ing of the series-resonant coil"-5;'- 1=Thisircuit will produce oscillations at the lower reson ntfrequency of the circuit and suppress the fifth harmonic determined by high resonant frequency of the circuit. The currents at the two resonant frequencies are in opposition in the second coil 5 and regeneration occurs only at the lower frequency' with the connection shown to the third coil 2. I j

It will be understood that th method of coupling the' control electrode and anode circuit may be varied in accordance with recognized engiculating the values of P and Q in Fig. 1 for any combination of frequencies in a bi-resonant circuit:

when, f2=nf1, and n is any value, integral or non-integral ellet p7 The series-resonant circuit determines a zero impedance point at a frequency between the two resonant, frequencies of the complete circuit. .At frequencies below the point of zero impedance,

the series-resonant circuit exhibits a capacitative' reactance, while at frequencies above this point it exhibits an inductive reactance.

By varyingthe product PQ, the frequency of the zero impedance'point can be varied, and the relative impedances of both resonant peaks can be varied; Byproper selection of the values of P and Q, thedegree of accentuation or suppression of both resonant frequencies can be determined for thecircuit of Fig. 4, since all currents are in phase in the coi1'3. However, since the currents of the two frequencies are in phase opposition in the coil 5', the circuits of Figs. 5 and 6 are capable of r producing oscillations at only one of the resonant frequencies, depending on the reaction with the coupling coil 2.

It will be understood that a plurality of series resonant circuits can be connected in parallel with r the parallelresonant circuit to provide three or more resonant responses.

I claim as-my invention:

1. An oscillator including an'electron discharge tube including control electrode and anode electrode circuits, a mul'ti-resonant network including a parallel resonant circuit and a series resonantcircuitconnected across said parallel resonant circuit, said network being connected in one of said! tube electrode circuits, and aperiodic means for couplin the other of said tube electrodecircuits to said multi-resonant network to produce oscillations of predetermined amplitude at all: resonant frequencies of said multi-resonant network;

2. An oscillator having an electron tube including: catl10de,,anode: and control electrode circuits, & network in the anode circuit of said tube ineluding a parallel resonant circuit and a series resonant circuit connected across said parallel resonant circuit, and aperiodic means for coupling said control electrode circuit to said network.

3. An oscillation circuit having an electron tube including cathode, anode and control electrode circuits, a network in the anode circuit of said tube v comprising a parallel resonant circuit and a series resonant circuit connected across said parallel resonant circuit, and aperiodic means for coupling said control electrode circuit to said parallel resonant circuit.

4. An oscillation circuit having an electron tube including. cathode, anode and control electrode circuits, a network in the anode circuit of said tube comprising a parallel resonant circuit and a series resonant circuit connected across said parallel resonant circuit, and aperiodic means for coupling said control electrode circuit to said series resonant circuit.

5. An oscillation circuit having an electron tube including cathode, anode and control electrode circuits, a network in the anode circuit of said tube comprising a parallel resonant circuit and a series resonant circuit connectedacross said parallel resonant circuit, and aperiodic means for coupling said control electrode circuit to both said parallel resonant circuit and said series resonant circuit.

6. An electron discharge tube oscillator circuit including control electrode and anode circuits, a multi-resonant network including a parallel resonant circuit and a series resonant circuit connected across said parallel resonant circuit, said network being connected in said anode circuit and aperiodic means for coupling said control electrode circuit to said multi-resonant network,

to provide oscillations at all resonant frequencies of said mul'ti-resonant network. 7

"I. An electron discharge tube oscillator circuit including control electrode and anode circuits, a multi-resonant network including a parallel resonant circuit and a series resonant circuit connected across said parallel resonant circuit, said network being connected in said anode circuit and aperiodic means for coupling said control electrode circuit to said multi-resonant network to provide oscillations at some resonant frequencies and suppress oscillations at other resonant fre-' quencies of said multi-resonant network.

8. An electron discharge tube oscillator circuit including control electrode and anode circuits, a multi-resonant network including a parallel resonant circuit and a series resonant circuit connected across said parallel resonant circuit, said network being connected in said anode circuit and aperiodic means for coupling said control electrode circuit to said multi-resonant network to accentuate the amplitude of predetermined harmonies of the lowest resonant frequency of said multi-resonant network.

9. An electron discharge tube oscillator circuit including control electrode and anode circuits, a multi-resonant network including a parallel resonant circuit and a series resonant circuit connected across said parallel resonant circuit, said network being connected in said anode circuit and aperiodic means for coupling said control lectrode circuit to said multi-resonant network to suppress the amplitude of selected harmonics of the lowest resonant-frequency of said multi-resonant network.

WILLIAM D. HERSHBERGER. 

